Treacher-Collins syndrome

Treacher Collins syndrome (TCS), also known as mandibulofacial dysostosis or Franceschetti-Zwahlen-Klein syndrome, is a rare genetic disorder affecting the development of bones and other tissues of the face. It is caused by mutations in the TCOF1 gene (most commonly, accounting for approximately 78-93% of cases), POLR1C gene, or POLR1D gene, all of which play critical roles in ribosomal RNA biogenesis and craniofacial development during embryogenesis. The condition primarily affects structures derived from the first and second pharyngeal arches. Key clinical features include bilateral and symmetric downward-slanting palpebral fissures (eye openings), coloboma (notching) of the lower eyelids with sparse or absent eyelashes on the lower lids, hypoplasia (underdevelopment) of the zygomatic bones and mandible (giving the face a characteristic flattened appearance), malformation or absence of the external ears (microtia or anotia), and conductive hearing loss due to abnormalities of the middle ear ossicles and external auditory canals. Cleft palate occurs in approximately 30% of affected individuals. The severity of the condition is highly variable, even within the same family, ranging from barely noticeable facial differences to severe craniofacial anomalies that can cause life-threatening airway compromise in newborns. There is currently no cure for Treacher Collins syndrome, and management is multidisciplinary and symptom-based. Treatment typically involves a coordinated team including craniofacial surgeons, otolaryngologists, audiologists, speech therapists, orthodontists, and psychologists. Airway management is the first priority in severely affected neonates, sometimes requiring tracheostomy. Hearing aids or bone-anchored hearing devices are used to address conductive hearing loss. Surgical reconstruction of the facial bones, ears, and eyelids is often performed in stages throughout childhood and adolescence. Early intervention with speech therapy and educational support is important to optimize developmental outcomes. Genetic counseling is recommended for affected individuals and their families.

Common questions about Treacher-Collins syndrome